LOS ANGELES — Arguing that free speech is being stifled at college campuses across the country, a Philadelphia-based advocacy group on Tuesday filed lawsuits against four universities, seeking to force the schools to revise policies that the group says restrict some forms of speech.

The group, the Foundation for Individual Rights in Education, singled out four schools that it says squelched free speech in noteworthy ways — by banning certain T-shirts on campus, for example, or by trying to shut down a faculty blog that criticized the administration — and said it planned to file dozens of similar lawsuits. By the group’s estimate, nearly 60 percent of public universities and colleges have restrictions on rights guaranteed by the First Amendment.

The lawsuits were filed after recent protests at several schools against scheduled commencement speakers, whom some on campus deemed inappropriate. Many of those invited to address graduating students ultimately declined to speak. Also this year, students at several colleges urged their professors to adopt policies warning them about potentially offensive content introduced in class.

“We’re cultivating an intellectually unhealthy attitude that it is not O.K., or even dangerous, to hear opinions that might make you uncomfortable,” said Greg Lukianoff, the president of the group filing the suits. “Universities have been much too shy in saying that there’s a great educational benefit from hearing dissent. You have a whole generation of people who think that they should be protected from anything they see as unwanted or disagreeable.”

The suits allege that both Iowa State University and Ohio University banned certain T-shirts; Chicago State University, tried to shut down a faculty blog; and Citrus College in Glendora, Calif., set limits on where a student could collect signatures for a petition.

According to the group, many colleges have adopted vague anti-harassment policies that ban speech deemed offensive, and that give administrators the power to quash all sorts of political debate, satire or art.

At Iowa State, a group of students involved with the campus chapter of the National Organization for the Reform of Marijuana Laws, or NORML, ordered T-shirts with the university mascot replacing the O in the organization’s logo, use that was approved by the university’s trademark office. After dozens of the T-shirts were sold on campus, however, school officials ordered the students to stop, arguing that the shirts implied that the university supported the legalization of marijuana.

A spokesman for the university, John McCarroll, would not comment on the pending litigation but said in a statement that “Iowa State has the right and obligation to manage the use of our university trademarks.”

At Ohio University, a group that provides help to students accused of misconduct on campus printed a T-shirt with the statement “We get you off for free.” Administrators ordered students in the group to stop wearing the shirts, saying they “objectified women” and “promoted prostitution,” according to the foundation’s complaint.

Ohio University, however, denies banning the shirts.

“Administrators never directed the students or the student organization to not wear the T-shirts mentioned in the lawsuit, and no student misconduct action was ever threatened or taken,” Katie Quaranta, a spokeswoman, said in a statement.

The two other schools being sued did not return requests for comment.

The group previously filed two similar lawsuits, including one last year against Modesto Junior College in California, after staff members told a student that he could not pass out copies of the United States Constitution outside the college’s “free-speech zone.” The college settled the lawsuit for $50,000 and dismantled the zone.